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Axis Commissioning Checklist Procedures
5.7
Optimizing the speed controller
Screen page SPEED CONTROLLER
1.
SETP. -OFFSET:
Leave the amplifier enabled. If the axis is drifting, alter the parameter Setp.-Offset until it stands still (or use the function
AUTO-OFFSET).
2.
SETP. RAMP +/-:
The setpoint ramps are used to smooth the setpoint input (filter effect).
Set the mechanical time constant for the complete system, i.e the rise time or ramp gradient for the speed from 0 to n
As long as the ramps that are set are shorter than the mechanical response time for the complete system, the response speed
will not be affected.
3.
LIMIT SPEED:
Set the desired final limit speed.
4.
KP/Tn:
Increase KP until the motor starts to oscillate (audible, and visible
on the oscilloscope) and then reduce KP again until the oscillations
have definitely stopped and stability is assured.
Use the motor-specific default value for Tn.
5.
Start reversing mode:
Start the reversing mode (F8, v1/v2 approx. +/-10% of n
Observe the speed response on the oscilloscope. If the settings are correct,
there must be a stable step response in both directions.
6.
KP:
You can produce a fine tuning of the speed response by cautiously increasing KP.
Aim: the smallest overshoot, but still retaining good damping.
A larger total moment of inertia make it possible to use a larger value for KP.
7.
PID-T2:
You can dampen out disturbances, such as a small amount of play in the gearing,
by increasing PID-T2 to about 1/3 the value of Tn.
8.
FEEDBACK:
You can further improve the smooth running by using FEEDBACK, especially for
small drives with a low torque.
9.
End reversing mode:
Finish the reversing mode operation (F9).
Set up the correct, motor-specific value for Ipeak (current controller) again. Start up reversing mode again, and
observe the step response. If there is any tendency to oscillation, reduce KP slightly.
Save the present parameter set in the EEPROM. Click on the
20
07/03
for the motor).
nom
Diagram: Step response
n
SW
t
1
2
= speed
= setpoint
= time
= optimum
= KP too high
button.
Setup Software
BECKHOFF
.
cmd
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